1. Field of the Invention
The present invention relates to an anti-bacterial water absorbing agent which has excellent water absorption performance, anti-bacterial performance, and powder flow properties. The anti-bacterial water absorbing agent is suitable for the manufacture of absorbent materials for absorbing urine, blood, and body fluids. The invention is further directed to a method of producing said agent and an absorbent material using said agent.
2. Description of the Related Art
Water absorbing resins are widely used in absorbent materials or absorbing articles including disposable diapers, incontinence pads, sanitary napkins, nursing pads, sheets for pets, absorbent materials for pets littex, excretion treating agents, waste blood gelling materials, drip absorbers, and freshness retaining materials. These devices rely on the water absorption/retention capacities and gelling properties of the resin. Although the conventional water absorbing resins have excellent absorption/retention capacities for urine, blood, and other body fluids, these prior materials do not have anti-bacterial properties.
Therefore, when the water absorbing resin absorbs urine, blood, and other body fluids, the organic materials contained in the liquids being absorbed are degraded by bacteria, fungus and other microorganisms, thereby causing, for example, malodors, skin irritations, and rashes. Furthermore, the resulting hydrogels are also easily putrefied by the bacteria in the air resulting in the development of odors. To overcome these problems, materials which exhibit both absorption and anti-bacterial properties are desired to provide a hygienic and safe environment. The development of odors and rashes is a serious problem in absorbent materials such as disposable diapers for the bedridden elderly and the sick, so that an early solution to the problem is desired.
Several materials have been proposed for controlling odor and bacterial growth in absorbent materials. One example is a powder mixture of a water absorbing resin and a zeolite as disclosed in Japanese Kokai Nos. 57-25813, 59-179114, and 59-189854. Another example includes a composition of activated carbon coated with a water absorbing resin as disclosed in Japanese Kokai No. 56-31425. A further composition consisting of a water absorbing resin and a deodorant component extracted from camellia is disclosed in Japanese Kokai No. 60-158861. A water absorbing resin composition containing a specific anti-bacterial agent of benzalkonium chloride, chlorhexidine gluconate, and various phosphates is disclosed in Japanese Kokoku No. 4-17058, and Kokai No.5-179053. These compositions have been proposed for use in the manufacture of absorbent materials.
However, these prior compositions are not entirely satisfactory in controlling odors and preventing putrefaction of fluids in an absorbent material. These water absorbing resins require treatment with an anti-bacterial compound to provide anti-bacterial and deodorant activity. In addition, the powder flow property is degraded by the treatment which is necessary to provide the anti-bacterial and deodorant activity.
The prior compositions which include a mixture of a water absorbing resin and a zeolite can adsorb some odors. However, since neither the water absorbing resin nor the zeolite have anti-bacterial effect, the composition cannot suppress putrefaction of organic materials caused by bacteria, fungus or other microorganism, and cannot suppress the development of odors. In addition, the conventional absorbent materials cannot prevent the occurrence of skin irritations and rashes. The separation of the zeolite from the water absorbing resin by shaking or impacting increases the likelihood of dust particles becoming airborne. In addition there is a wide variation in the odor control activity of the resulting composition.
Compositions of activated carbon coated with a water absorbing resin and compositions consisting of a water absorbing resin and a deodorant component extracted from camellia, are also not able to suppress putrefaction of organic materials caused by microorganisms and fungus, since the activated carbon and the deodorant component extracted from camellia have no anti-bacterial activity.
A water absorbing resin compound containing a benzalkonium chloride, chlorhexidine gluconate, or phosphate exhibits anti-bacterial effect to some extent, but generally is not satisfactory. This composition has limited effectiveness in controlling or suppressing the growth of certain kinds of bacteria, fungus and other microorganisms. Further, the powder flow property of the water absorbing resin treated with the anti-bacterial agent is considerably reduced depending on the amount of the anti-bacterial agent used.
Furthermore, special steps or operations are required to fix a zeolite, activated carbon, or a deodorant extracted from camellia to the water absorbing resin. Accordingly, a need exists for improved water absorbing compositions having water absorbent and anti-bacterial properties.